The present invention relates, in general, to centering a pipe and, more particularly, to centering a casing within a wellbore.
A wellbore is the physical hole that makes up a well and can be open or cased, or a combination of both, and can extend miles deep within the earth. The wellbore can be routed vertically or horizontally with respect to the above surface. Further, the wellbore can be routed through a variety of strata or layers containing valuable water and natural gas sources. After the wellbore is completed, a well casing is typically inserted into the wellbore. The well casing is inserted into the wellbore to prevent collapsing of the wellbore, to prevent cross-contamination between the earth's various layers and to provide a pressure boundary for the well.
After installing the casing in the well, cement is typically pumped into an annular space between the casing and the drilled hole or wellbore. Once hardened, cement prevents fluid flow between strata of the earth and allows selective production from zones of interest, typically oil and gas. Proper cement placement requires that the casing is centralized in the well bore to ensure uniform annular space. Centralizers are used to keep a uniform annular space between the wellbore and the casing. This is achieved by protrusions disposed on the outside of the centralizer. To keep the casing centered within the wellbore, the position and shape of the protrusions are important to maintain the appropriate orientation of the casing and minimizing annular volume restrictions and drag forces while installing the casing in the wellbore.
During installation of the well casing, the protrusions can be exposed to rigorous forces including rotational or axial movement on the centralizer. Hence, the protrusions of the centralizer need to be strong to prevent breakage from stresses during installation and from subsequent drilling.
Hence, there is a need for a centralizer having improved protrusions to help prevent cement voids and have sufficient strength to prevent breakage.